Numeric

The T9 / Phone Code Cipher is based on the multi-tap input method used on traditional numeric keypads. Each digit key corresponds to multiple letters, and the number of presses determines which letter is selected. Spaces between words are preserved.

The Nihilist Cipher is a polygraphic substitution cipher that combines the principles of the Polybius Square with a numeric key to produce a series of ciphertext numbers. It was developed in the 19th century by Russian nihilists to securely transmit messages, hence its name. Each letter is first converted into a pair of digits using a Polybius grid, then combined with corresponding digits from a numeric key by addition, resulting in ciphertext that appears as a sequence of numbers.

The Letter Number Substitution cipher is a simple substitution system in which each letter of the alphabet is replaced by its corresponding numeric position. For example, A=1, B=2, …, Z=26. This cipher is sometimes called the A1Z26 Cipher and is one of the most straightforward methods to convert letters to numbers for encoding messages.

The Knapsack Cipher is a public-key cryptosystem based on the mathematical problem of the subset sum, also known as the "knapsack problem." It was one of the first attempts at a public-key encryption scheme, proposed by Ralph Merkle and Martin Hellman in 1978. The cipher transforms a plaintext message into a binary representation and encodes it as a sum of elements from a specially chosen sequence, making decryption without the private key computationally difficult.

The Rout Cipher is a columnar transposition cipher that rearranges letters of a plaintext into a grid defined by a keyword. Letters are then read off column by column in alphabetical order of the keyword letters. Spaces are removed during encoding, and if the last row is incomplete, it may be padded to fill the grid. The recipient decodes by reconstructing the grid and reading row by row.

Its security relies entirely on the secrecy of the keyword. It does not substitute letters but only rearranges them.

The ROT Cipher is a simple monoalphabetic substitution cipher that shifts each letter of the plaintext by a fixed number of positions in the alphabet. “ROT” stands for “rotate,” and the most common variant is ROT13, which shifts letters by 13 positions. This means that A becomes N, B becomes O, and so on, wrapping around the alphabet. Because the English alphabet has 26 letters, applying ROT13 twice restores the original text.

The Pinprick Cipher is a simple symbolic substitution cipher in which letters are represented by patterns of dots (·) and circles (o). It works by assigning a unique sequence of these symbols to each letter, making it easy to encode short messages while hiding them in plain sight. Its origin is somewhat obscure, but it was historically used for secretive or playful communications, often in correspondence or small notes.

The Null Cipher is a steganographic technique that hides a secret message within an ordinary-looking text. Most letters in the text are "nulls" and do not convey information, while only certain letters—determined by a prearranged rule—carry the hidden message. Its security relies on subtlety: without knowledge of the extraction rule, the cover text appears completely normal.

The Gronsfeld Cipher is a variant of the Caesar Cipher that uses a numeric key to perform multiple shifts on the plaintext. Named after the German banker Baron Gronsfeld in the 19th century, it operates like a Caesar shift but allows each letter to be shifted by a different amount based on the corresponding digit of the key.

A Dice Cipher, also known as a Dice Cryptography or a Book Cipher, is a cryptographic technique that uses dice as a randomization tool to generate a series of numbers that correspond to words or characters in a pre-selected reference book. It is a form of polyalphabetic substitution cipher.

Here's a general overview of how a Dice Cipher works: